Doing some work on upgrading our Zimbra box... Does zimbra support hyperthreading? Are there any issues with it? Using FC4 - will probably be upgrading to FC5.

Thanks,
Rob

Yes. Use Hyperthreading. The "fake" CPU does a good enabling some basic optimizations for lots of independent processes (which Zimbra falls into it). In my experience it makes about a 10% different with a SMP Friendly workload.